This invention relates to a system which interprets compressor operational factors, and monitors these factors to identify irregularities. Moreover, the system stores the factors, thus providing a record.
Compressors are utilized to compress a refrigerant as part of a refrigerant cycle in cooling systems. Modern compressors for refrigerant compression are typically enclosed in a sealed housing. The compressors are driven by a motor which is driven by a single phase or a three phase power supply. Compressors operate under many extreme conditions. Some compressors have relatively complex operational parts. In one popular modern type compressor, two spiral scroll wraps orbit relative to each other to compress entrapped refrigerant. While scroll compressors are gaining wide popularity, they also are subject to design challenges. As an example, if the compressor is not optimally designed, there is a possibility of the scroll members orbiting in an improper xe2x80x9creversexe2x80x9d direction at shut down. Moreover, if the compressor is improperly wired, such reverse rotation can occur.
Other problems occur with compressors generally, but raise particular concerns in scroll compressors. Each type of compressor has specific vulnerability situations. As an example, an overcharge of refrigerant or low charge of refrigerant can be detrimental. The operation of compressors generally for refrigerant cycles have many additional challenges. As one example, stalling of the motor can indicate various problems. Also, a problem with other aspects of the refrigerant system can be identified at the compressor. As an example, if the outdoor fan fails, there will be potential increased temperatures which can be sensed at the compressor.
To date, compressors have typically been manufactured with a plurality of protection devices at each of the various components which are to be protected. As an example, the electric motor for driving a sealed compressor is typically provided with a protection switch which is actuated if a predetermined temperature is reached to stop the motor. Moreover, various protection valves are incorporated into the compressor members, and in particular, the scroll members, and are actuated under certain circumstances.
It would be desirable to minimize and simplify the number of protection devices incorporated into a compressor. Moreover, when a compressor does fail, the manufacturer would like to have some indication of why the compressor failed. To date, the manufacturer can only make interpretations of the likely cause of failure.
In a disclosed embodiment of this invention, a control receives signals relating to a number of operational factors in a compressor. Preferably, the discharge temperature and pressure, the suction temperature and pressure, and the power to the motor are all sensed. The control may also receive an indication of other temperatures, such as the temperature in an oil sump for the compressor.
All of these factors are sent to the control, which is preferably a microprocessor based control. The microprocessor based control is designed to interpret these various factors and compare the sensed factors to predetermined minimums, maximums, relationships, at the earliest etc. to determine a fault condition. Moreover, the control is preferably provided with a memory that is able to store previously read factors. The memory serves two functions. First, a xe2x80x9ctrendxe2x80x9d in any of the factors can be identified. As an example, if one of the sensed temperatures is gradually increasing over time, this may be indicative of a xe2x80x9cslow leakxe2x80x9d in the system, or other slowly approaching fault problem.
In addition, the memory stores the sensed information for later retrieval. Thus, should the compressor fail, a maintenance worker can access the information from the control and have a very good indication of why the particular compressor failed. This function of the memory may be xe2x80x9cshort term.xe2x80x9d That is, it may be only a very recent time period which is stored in the memory. On the other hand, the memory could be over a very long period of time. Further, the memory may only store xe2x80x9cfeaturexe2x80x9d information. As an example, the memory may be configured to only store a high and a low of each of the features for each calendar day. Alternatively, the memory could also be designed such that it only stores the previous time, such as two days. The previous two days would provide the control with the ability to identify trends, but would not require an undue amount of memory. Moreover, if the compressor fails, the memory would still store the most recent feature information, and thus should provide an indication of why the failure occurred.
These and other features of the present invention can be best understood from the following specification and drawings, the following which is a brief description.